Introduction

What is structure data ?

Nuclear stucture data refer to
the properties of single nuclei, as opposed to reaction data which deals
with the properties of a nucleus interacting with radiation or another
nucleus.

Numerical data related to nuclear
structure are available in the ENSDF and NUDAT databases, and bibliographic
information on nuclear structure is found in the NSR database.

The Nuclear Structure and Decay Data Network

The International Nuclear Structure and Decay Data
(NSDD) Network
is organised under the auspices of the International
Atomic Energy Agency, and co-ordinated by the National Nuclear Data Center
(NNDC) at the Brookhaven National Laboratory, US. The NSDD Network is
responsible for the evaluation of all the mass-chains on a continual basis.
A mass-chain is formed by all the nuclides of the same mass and different
chemical elements. Each of the members of the network has a permanent
assignment of mass-chains depending on the number of evaluators, their
research interests, or special expertise in a particular mass region.
Evaluations produced by the NSDD Network are stored in the Evaluated Nuclear
Structure Data File (ENSDF) database. Links to data centres in the NSDD Network is available from
NNDC

The ENSDF database

Contents of the ENSDF database

ENSDF contains evaluated experimental
data summarizing the present knowledge on the structure and decay of nuclei.
It contains information on nuclear level properties, radiations, radioactive
decay, and reaction data for all known nuclides. For masses A ≥ 45,
this information is documented in the Nuclear Data Sheets; for
A < 45 ENSDF is based on compilations published in the journal Nuclear Physics.

If there are gaps in experimental
data, they are not filled with theoretical or nuclear model calculations.
While the emphasis is on experimental data, the evaluations do use well-founded
systematics or theory.

General Organisation of the ENSDF data

The Evaluated Nuclear Structure
Data File is made up of a collection of "data sets" which present
one of the following kinds of information:

The evaluated results of a single experiment.
e.g., a radioactive decay or a nuclear reaction.

The combined evaluated results of a number of experiments of the same kind.
e.g., (Heavy ion, xn gamma), Coulomb excitation, etc.

The adopted properties of the nucleus.

The references used in all the data sets for the given mass number.
This data set is based upon reference codes (key numbers) used in various data sets for a given
mass number and is added to the file by NNDC.

The data sets in ENSDF are organised
by their mass number. Within a mass number the data sets are of two kinds:

Data sets which contain information pertaining to the complete mass chain.
These data sets contain information of the type (4) and (5) given above.

Data sets belonging to a given nucleus (Z-value).

Data sets (ii) i.e., for a given nucleus (Z-value), consist of the following:

Adopted data sets (only one per Z-value) giving adopted properties of the levels and radiations seen in that nucleus.

Data sets giving information of the type (1) or (2) above.

If the is more than one data set of type (1) or (2)
for a given nucleus, then an adopted data set is required for that
nucleus. If there is only one data set for a given nucleus, then that set
is assumed also to present the adopted properties for that nucleus.

Search NUDAT database

This mode of access provides
an easy way to make simple searches of the NUDAT database. The opening
screen invites the user to select the type of data desired (selected from
the list of data types shown above). For all data types the chemical symbol
(or atomic number) and mass number are offered as search parameters. The
other search parameters available are dependent on the data type. A full
desciption of possible search criteria, together with examples, can be
found on the web page "The
NuDat2 Description".

Audi/Wapstra Mass Evaluations

General Information

The AME2003 atomic mass evaluation" is presented here in the form of four files:

The last three files with names
mass_exp.mas95, rct1_exp.mas95 and rct2_exp.mas95 are identical to the
first three files except for the values resulting from the use of the
few deviating experimental data, listed in Table~B of Ame'93 and updated
in Table~IV-a of Ame'95.

Values in these files are exact (unrounded) copy of the published ones.

They can conveniently be used for calculations.

They should not be copied in a publication as given in these files, but instead, rounded
values, as published in the above Journal should be used.